| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a compact metal halide discharge lamp for direct-current lighting suitable for an automobile headlamp which can suppress crack occurrence in a sealing part of a positive electrode side; a metal halide discharge lamp lighting device equipped with it, and to provide a lighting system. <P>SOLUTION: This metal halide discharge lamp MHL is provided with an airtight vessel 1, having a surrounding part 1a and a pair of sealing parts 1b with sealing metal foil pieces embedded airtightly in the inside; a positive electrode 2A and a negative electrode 2K having base ends connected to the sealing metal foil pieces 3A and 3B, respectively, and electrode main parts, facing to the inside of the surrounding part by separately facing to each other, and intermediate parts supported by the sealing parts; a pair of current introducing conductors 4A and 4B; and a discharge medium containing a first halide, a second halide and a rare gas that essentially does not contain mercury. In the metal halide discharge lamp, the direction of a current flowing in the airtight vessel is a single direction that does not change with the time, at all times; the length of the sealing metal foil piece on the positive electrode side is larger than that of the sealing meta foil piece on the negative electrode-side, and its length is set to 10-19 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
